A friend goes to Hawaii every year and brings back a sack or two of macadamia nuts in the shell. When he tries to crack the nuts with a hammer, the force required is so great that he crushes the meat of the nut, too, when the shell finally yields. He needed a special nutcracker. Here you see it in use.
Step 1: Make Teeth in the Jaws
When machining needs to be done on a smaller piece that would be difficult to hold I like to do the machining first and then cut the piece away from the larger bar stock. Use a thin cutting wheel to make teeth on the jaws. It does not matter that the jaws resemble a square wave rather than saw teeth. One of the jaws will be 1 3/4 inches long. When the teeth have been cut for it, cut it away from the bar stock.
Cut identical teeth for a second jaw and make them over a length of 1 3/4 inches, also. These teeth are enough to grasp the shell of a nut and hold it while it is being cracked.
Step 2: Cutting the Second Jaw
Step 3: Prepare to Weld
The first pass is called a root weld. After welding a bead on one side, turn the assembly over and make a bead on the other side. Alternating sides for welding like this minimizes distortion by heating both sides evenly. Clean away slag before laying down a new weld bead. Be careful to avoid any slag inclusions. Trapped slag will make a weaker weld.
Step 4: Weld Completed (for Now)
The first jaw made is shown in the approximate position it will have when the nutcracker is finished. An axle on which it can rotate will need to be added, but first there is something else that needs to be done.
Step 5: Fitting Welded to Backside of the First Jaw
Weld a bar of 3/16 x 3/4 inch stock to the back of the first jaw, but make it offset from the side face that is against the aluminum I am using as a welding table. The offset is 3/8 inch. I used a piece of wood this thickness. I also cut the end of the bar stock at a slight angle so the fitting angles upward just a little. I used 20 degrees as my angle.
Step 6: Cut the Bar Stock and Drill a Hole
Step 7: Weld an Axle for the First Jaw
Step 8: Cut Two Pieces and Drill
Step 9: Clean Up the Axle
Step 10: Dry Fit the Pieces From Step 8
Step 11: Weld the First Jaw to Its Mounts
With the two jaw mounts from step 8 fitted over the axle ends, insert the first (movable) jaw between them. Position the jaw as desired and clamp in place for a couple of tack welds. Be certain the jaw and its mounts have a good range of unrestricted movement before tack welding. Then remove the clamp and weld wherever there is space for a bead. I welded some on the backside of the first jaw from the right side of the photo, as well as on top of the jaw mount pieces.
This nutcracker is primarily for macadamia nuts. The smallest macadamia nuts are about 5/8 inch in diameter. The bottom area of the jaws is spaced for 5/8 inch in the photo.
Step 12: Add a Second Axle
Step 13: Make an Actuating Lever
Notice that the distance between the axle hole(s) in the lever is less than that in the movable jaw. This means considerably more movement is required in the lever for considerably less movement in the jaw. This acts as a force multiplier.
Step 14: Make Four Squares With Holes
Step 15: Thicken the Lever for a Better Bearing Surface
Step 16: Weld a Permanent Nut Onto the Axle End
Place one of the hole squares over the end of the axle. Press it against the base of the nutcracker. Weld the end of the axle to the hole square for a permanent nut or retainer. The photo is actually from a later step, but illustrates this step well.
Step 17: Connect the Lever to the Movable Jaw
How long should connecting bar between the lever's 2nd hole and the fitting on the back of the movable jaw be? I placed a macadamia nut in the jaws at about mid-range and secured the jaws with a spring clamp. Then I moved the lever to its most rearward position likely to be comfortable for normal use. I measured on center between the two holes and got a figure of 4 7/8 inches. I cut a piece of bar stock 5 5/8 inches long and drilled two 5/16 inch holes 4 7/8 inches distant from one another on center. As before, remove all burrs.
Step 18: Install the Connecting Rod
Step 19: Add Another Permanent Nut
Repeat this process for the other end of the connector at the remaining pivot point behind the movable jaw. Weld the short piece of rod to the fitting behind the movable jaw. Weld a hole square over the other end of the round rod protruding through the connector.
Step 20: Mechanism Operational
Step 21: Drill a Mounting Hole
One 1/4 inch hole and bolt at the very back end of the nutcracker takes advantage of the forces used when cracking a nut and is sufficient. Here you see the mechanism turned upside down for drilling behind the lever's axle.
Step 22: Cut the Base to Length
Step 23: Add a Long Handle
Step 24: 2 X 4 Mount
I mounted the mechanism on a piece of 2 x 4 lumber 18 inches long. I inletted the 2 x 4 so the mechanism fits tightly on it. I drilled a hole through the 2 x 4 for the mounting bolt. I made a recess for a Tee-nut to receive the bolt. I added some extra inletting wherever it appeared moving parts might be hindered by wood from the 2 x 4.
Step 25: How to Use
Place a nut in the jaws where the nut fits when the jaws are fully open. See step 17, right side of the photo, or the photo in the Introduction. Pull down on the handle with a slow, firm pressure. When you hear the shell of the nut crack, stop pulling on the handle. My friend likes to cup his hand around the nut as it is being cracked. It keeps the meat of the nut from rolling away. The photo shows the results when you successfully crack a macadamia nut. The shell is opened, but the meat is not damaged.
Although the jaws for this nutcracker do open far enough to hold a black walnut, I would not advise using it with black walnuts. Use a hammer on those and pick the meats out in pieces. But, this nutcracker would work with properly sized filberts or hazelnuts, Brazil nuts, English or California walnuts, and others,